Solid Electrolyte Films Research Articles

Preparation of a new nanoconductive ROMP copolymer and its application as solid polymer electrolyte

New thermoplastic host copolymer based on oxanorbornene dicarboximides for solid polymer electrolytes was synthesized and characterized by spectral methods. The corresponding new nanoconductive ROMP copolymers were prepared through doping of lithium salt, LiBF4. The effect of lithium concentration on the conduction behavior of new SPEs was studied. The conductivity measurements were carried out on thin films of the nanostructured solid polymer electrolytes. The maximum conductivity (1.27×10−5Scm−1) was obtained for a copolymer complex with 10wt.% LiBF4.

Microstructure and ionic conductivity of lithium-aluminum titanophosphate

Synthesis from aqueous peroxide solutions provides lithium-aluminum titanophosphate Li1.3Al0.3Ti1.7(PO4)3 (LATP) with particles of submicron size and conductivity of (4–5) × 10−4 S/cm at the room temperature. LATP were characterized using the methods of XRD, DTA/TG, measurement of specific surface area, ionic and electronic conductivity. According to XRD, a single-phase crystalline product with the specific surface area of 8.2 m2/g is formed as a result of precursor sintering at 700°C (the average particle size of electrolyte was 250 nm). Sizes of coherent-scattering region were calculated on the basis of the values of intrinsic broadening of diffraction maximums. Analysis of broadening of diffraction maximums indicates that the size of primary LATP crystallites after sintering at 700°C was 90 nm according to peak (113) (2θ = 24.5°) and 110 nm according to peak (104) (2θ = 20.9°). The synthesized submicron LATP powders are suitable for formation of solid electrolyte films using the method of aerosol deposition.

Performance Characteristics of Pyrazole as an Effective Dopant in a Blended Polymer Electrolyte for Nanocrystalline Dye-Sensitized Solar Cell Applications

Thin films of nanocomposite blended solid polymer electrolyte consisting of polymethyl methacrylate (PMMA)/polyvinylidene fluoride (PVDF), potassium iodide (KI) and iodine (I 2) as redox couple and pyrazole (PYR) as dopant were prepared using solution casting technique. The consequences of inclusion of PYR within PMMA/PVDF/KI/I 2 were investigated in terms of photovoltaic performance of the cell whereas the PYR impregnated polymer electrolyte solution when introduced into dye-sensitized solar cells (DSSCs) exhibited an overall energy-conversion efficiency of 5.5% at room temperature under AM1.5 illumination.

Lithiated and sulphonated poly(ether ether ketone) solid state electrolyte films for supercapacitors

Poly(ether ether ketone) (PEEK) films have been synthesised and used as solid-state electrolytes for supercapacitors. In order to increase their ion conductivity, the PEEK films were sulphonated by sulphuric acid, and various amounts of LiClO4 were added. The solid-state electrolyte films were characterised by Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and thermogravimetric analysis. The ionic conductivities of the electrolyte films were analysed by performing electrochemical impedance spectroscopy. The obtained electrolyte films can be sandwiched or directly coated on activated carbon electrodes to form solid-state supercapacitors. The electrochemical characteristics of these supercapacitors were investigated by performing cyclic voltammetry and charge–discharge tests. Under an optimal content of LiClO4, the supercapacitor can provide a capacitance as high as 190F/g. After 1000cycles, the supercapacitors show almost no capacitance fading, indicating high stability of the solid-state electrolyte films.

Transparent Junctionless Thin-Film Transistors With Tunable Operation Mode

Junctionless low-voltage transparent indium-zinc-oxide (IZO) thin-film transistors (TFTs) gated by SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -based solid electrolyte films are fabricated on glass substrates by a full room-temperature process. The attractive feature of such TFTs is that the channel and source/drain electrodes are the same ultrathin IZO film without any source/drain electrodes. The operation mode of such devices can be tuned from depletion mode to enhancement mode when the thickness of the IZO film is reduced from 30 to 10 nm. Devices operated in both modes show a small subthreshold swing of <; 120 mV/dec and a large current on/off ratio of >; 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> .

Effect of heat-treatment on the surface structure and electrochemical behavior of AlPO4-coated LiNi1/3Co1/3Mn1/3O2 cathode materials

The surface of LiNi1/3Co1/3Mn1/3O2 particles were modified by AlPO4. Influences of heat-treatment on coating were studied by X-ray diffraction (XRD) and thermal analysis. Electrochemical tests and electrochemical impedance spectroscopy (EIS) were conducted. The results show that AlPO4 can react with LiNi1/3Co1/3Mn1/3O2 and an aluminum-containing-spinel phase of M′1M2O4 (M = Ni, Co, Mn, M′ = Al) is formed at above 700 °C. The high surface content of aluminum is in favor of forming a stable solid electrolyte film (SEI) on the surface of LiNi1/3Co1/3Mn1/3O2 during the first-two-charge–discharge processes. NO3− from the coating process may have reacted with LiNi1/3Co1/3Mn1/3O2. The resultant decompose at the temperature of above 400 °C. Existence of NO3− in the cathode is harmful to its electrochemical properties. The LiNi1/3Co1/3Mn1/3O2 coated with 1 wt% AlPO4 delivers a high discharge capacity and shows excellent capacity retention at 55 °C/0.5 C.

Preparation of powders and films of the lithium ion conducting solid electrolyte Li1.3Al0.3Ti1.7(PO4)3

This paper describes a process for the preparation of powders and films of the lithium ion conducting solid electrolyte Li1.3Al0.3Ti1.7(PO4)3 from peroxide solutions. The use of peroxide solutions ensures the preparation of Li1.3Al0.3Ti1.7(PO4)3 with a room-temperature electrical conductivity of (4–5) × 10−4 S/cm by calcining a precursor at 800°C. The synthesized Li1.3Al0.3Ti1.7(PO4)3 powders were characterized by X-ray diffraction, thermal analysis (DTA/TG), and ionic and electronic conductivity measurements. The growth of Li1.3Al0.3Ti1.7(PO4)3 solid electrolyte films is described.

Fabrication and Characterization of Li7La3Zr2O12 Thin Films for Lithium Ion Battery

The last few decades have seen a drastic miniaturization of electronic devices following the famous Moore’s law predicted by Gordan Moore in 1971. These developments in the electronic industry have resulted in ultra-low-weight electronic devices such as palm-top computers, smart phones, tablet PCs etc. Batteries constitute one of the most important and essential components of these devices. At present, lithium ion batteries (LIBs) are considered the most suitable candidateforuseinportableelectronicdevices.However,thesebatteriesare available only in the bulk form and comprise a significant percentage of the overall weight of the device. As the miniaturization of electronic devices continues, we need more advanced batteries which are light weight, safe, and environment friendly. One possible solution is the development of thin film batteries (TFBs) which can be integrated onto the microprocessor chips themselves. For these applications, we would require solid-state (SS) electrolyte. Currently, a major obstacle in this field is the low ionic conductivity of SS electrolytes and high temperature needed to fabricate thin films of these materials. As far as the research in SS electrolyte materials is concerned, many different kinds of inorganic systems have been explored to date. These include Nasicon-type electrolytes, 1‐4 perovskite-type lithium lanthanum tantantes, 5,6 and garnet-type Li ion conductors. 7,8 Among all of them, garnet type Li7La3Zr2O12 (LLZO), synthesized lately by Weppner’s group 9 has been reported to possess very high ionic conductivity. What’s more, LLZO is electrochemically stable with a potential window wider than 0‐7 V, is environment friendly, and is relatively inexpensive. 9‐11 However, to our knowledge, LLZO has so far been synthesized in bulk form only; no work has been reported on the preparation of LLZO thin films. For realizing thin film batteries, it is essential to be able to grow thin films of solid electrolytes and preferably at low temperatures. In this paper, we are reporting the fabrication of LLZO thin films on SrTiO3 (100) and Sapphire (0001) substrates by pulsed laser deposition at room temperature. The effect of annealing was investigated by detailed characterization of thin film structures and properties. Studies were also performed to understand the influence of lithium loss during the deposition process.

Electrical Characterization of Ultrathin Film Electrolytes for Micro-SOFCs

The reliability of solid oxide fuel cells (SOFCs) particularly depends on the high quality of solid oxide electrolytes. The application of thinner electrolytes and multi electrolyte layers requires a more reliable characterization method. Most of the investigations on thin film solid electrolytes have been made for the parallel transport along the interface, which is not however directly related to the fuel cell performance of those electrolytes. In this work an array of ion-blocking metallic Ti/Au microelectrodes with about a 160 μm diameter was applied on top of an ultrathin (1 μm) yttria-stabilized-zirconia/gadolinium-doped-ceria (YSZ/GDC) heterolayer solid electrolyte in a micro-SOFC prepared by PLD as well as an 8-μm thick YSZ layer by screen printing, to study the transport characteristics in the perpendicular direction relevant for fuel cell operation. While the capacitance variation in the electrode area supported the working principle of the measurement technique, other local variations could be related to the quality of the electrolyte layers and deposited electrode points. While the small electrode size and low temperature measurements increaseed the electrolyte resistances enough for the reliable estimation, the impedance spectra appeared to consist of only a large electrode polarization. Modulus representation distinguished two high frequency responses with resistance magnitude differing by orders of magnitude, which can be ascribed to the gadolinium-doped ceria buffer electrolyte layer with a 200 nm thickness and yttria-stabilized zirconia layer of about 1 μm. The major impedance response was attributed to the resistance due to electron hole conduction in GDC due to the ion-blocking top electrodes with activation energy of 0.7 eV. The respective conductivity values were obtained by model analysis using empirical Havriliak-Negami elements and by temperature adjustments with respect to the conductivity of the YSZ layers.

Metal supported tubular solid oxide fuel cells fabricated by suspension plasma spray and suspension high velocity oxy-fuel spray

Low temperature (LT) metal supported solid oxide fuel cells (SOFCs) have many advantages in comparison to conventional electrode or electrolyte supported type SOFCs. NRC has demonstrated high performance LT metal supported planar SOFCs fabricated by either wet colloidal spray/sintering or suspension thermal spray. The combination of tubular configuration and metal supported SOFCs may produce more unique and very attractive advantages such as easy and inexpensive sealing method and materials, high specific and volumetric power density, cost-effective fabrication, enhanced robustness, rapid start up, red-ox cycle tolerance and potential use for a pressurized integrated system.In this paper, thin film solid electrolyte of Sm0.2Ce0.8O1.90 (SDC) and NiO-SDC composite anode on sintered porous tubular metal supports were deposited by suspension HVOF spray and suspension plasma spray, respectively on sintered porous tubular metal support. La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) cathode on the SDC electrolyte was formed by wet colloidal spray and subsequent sintering process as the final fabrication step. The detailed investigation of suspension and process-related parameters for suspension thermal spray was performed in order to produce thin and crack-free SDC thin film coatings. The electrochemical performance of single cells was demonstrated.

Ge25Se75-based ReRAM 소자의 전계에 의한 저항 변화에 대한 연구

Resistance-change Random Access Memory(ReRAM) memory, which utilizes electrochemical control of metal in thin films of solid electrolyte, shows great promise as a future solid state memory. The technology utilizes the electrochemical formation and removal of metallic pathways in thin films of solid electrolyte. Key attributes are low voltage and current operation, excellent scalability, and a simple fabrication sequence. In this work, we investigated the nature of thin films formed by photo doping of <TEX>$Ag^+$</TEX> ions into chalcogenide materials for use in solid electrolyte of Resistance-change RAM devices and switching characteristics according to field-effect.

Low-Voltage Oxide-Based TFTs Self-Assembled on Paper Substrates With Tunable Threshold Voltage

Oxide-based thin-film transistors (TFTs) with a lateral in-plane electrode are self-assembled on paper substrates, and the electrical modulation effect of the in-plane electrode is investigated. A SiO2-based solid-electrolyte film with high specific capacitance is used as the gate dielectric, and the operation voltage is reduced to less than 2.0 V. The threshold voltage (Vth) of such paper TFTs is tuned from -0.98 to 0.94 V by different voltage biases on the in-plane electrode. The threshold voltage shift (ΔVth) can be described by ΔVth = -(CG2/CG1)VG2, where CG2 and CG1 are the in-plane electrode and bottom-gate specific capacitance values. High electrical performance with a current on/off ratio of 6 ×105 ~ 106, a subthreshold swing of 0.14 ~ 0.19 V/dec, and a mobility of 8.64 ~ 9.45 cm2/V·s is obtained at different in-plane electrode voltage biases. Such low-voltage paper TFTs are promising for low-cost and portable electronics.

Magnetron Sputtering Preparation of Nitrogen-Incorporated Lithium–Aluminum–Titanium Phosphate Based Thin Film Electrolytes for All-Solid-State Lithium Ion Batteries

We report for the first time a new lithium ion conducting Li–Al–Ti–P–O–N thin film solid electrolyte for all-solid-state lithium ion batteries. It was prepared by radio frequency (RF) magnetron sputtering deposition using a NASICON structural Li–Al–Ti–P–O target in a N2 atmosphere at various temperatures. XRD and SEM test results showed that the thin film was composed of an amorphous structure and that its surface was smooth, dense, and homogeneous. FTIR and XPS analyses indicated that nitrogen atoms were actually incorporated into the Li–Al–Ti–P–O matrix framework. The substitution of nitrogen for oxygen in the thin film created more abundant cross-linking structures and decreased the electrostatic energy, which favored the higher mobility of lithium ions. A high Li ionic conductivity of 1.22 × 10–6 S/cm was obtained for the thin film deposited at room temperature. Moreover, the higher value of 1.22 × 10–5 S/cm for the thin film deposited at 500 °C indicated that some crystallites in the amorphous film m...

Characterization of Li7La3Zr2O12 Thin Films Prepared by Pulsed Laser Deposition

ABSTRACTA pulsed laser deposition system was employed to fabricate thin films of Li7La3Zr2O12 solid electrolyte. The deposition process was carried out at room-temperature, resulting in amorphous films. These as-deposited films had a large optical band gap of 5.13 eV, and exhibited a lithium-ion conductivity of 3.35×10-7 S/cm. The films were then annealed, and the effect of annealing on the optical and electrical properties of the films was examined. After annealing at 1000 °C, the films were found to be cubic with a narrower band gap of 3.64 eV. In addition, these annealed films showed an inferior ionic conductivity than the as-deposited ones.

Solid electrolyte films in controlling their structures by electrophoretic deposition method

Improvement of proton conductivity of solid electrolyte films needs to form three-dimensional proton conduction paths by controlling the pore size and the pore structure between particles in particle films. A particle assemble method using electrophoretic deposition technique is useful for speedy and mass production assembly. In the electrophoretic deposition method, structure of particle array can be controlled by the electric field. As a result, the proton conductivity of the film showed a higher value for the regularly-arranged particle film and it is increased with a decrease in particle diameter. The proton conductivity of the film with the particles of diameter 50 nm had the highest value. The particle film with the well-controlled structure may enable the fuel cell to be operated in the middle temperature range.

The effects of thermal annealing on the structure and the electrical transport properties of ultrathin gadolinia-doped ceria films grown by pulsed laser deposition

Ultrathin crystalline films of 10 mol% gadolinia-doped ceria (CGO10) are grown on MgO (100) substrates by pulsed laser deposition at a moderate temperature of 400°C. As-deposited CGO10 layers of approximately 4 nm, 14 nm, and 22 nm thickness consist of fine grains with dimensions ≤∼11 nm. The films show high density within the thickness probed in the X-ray reflectivity experiments. Thermally activated grain growth, density decrease, and film surface roughening, which may result in the formation of incoherent CGO10 islands by dewetting below a critical film thickness, are observed upon heat treatment at 400°C and 800°C. The effect of the grain coarsening on the electrical characteristics of the layers is investigated and discussed in the context of a variation of the number density of grain boundaries. The results are evaluated with regard to the use of ultrathin CGO10 films as seeding templates for the moderate temperature growth of thick solid electrolyte films with improved oxygen transport properties.

Fabrication and Characterization of Solid Oxide Fuel Cell Electrolyte Films by Electron Beam Vapor Deposition

Thin films of SDC for SOFC electrolyte were prepared using electron beam deposition technique. The influence of annealing temperature, substrate temperature and e-beam gun power on the structure and surface morphology of the thin films was examined. It was found that the SDC thin films annealed at 800 degrees C consisted of a single cubic phase and the main crystal structure of the thin films represented those of evaporated electrolyte powders. The crystal orientation of the SDC films increased with substrate temperature and decreased with e-beam gun power. The higher XRD peak intensity was observed for the SDC films deposited on NiO-YSZ substrate compared with those on SiO2 substrate due to the polycrystalline structure of the NiO-YSZ substrate. A good adhesion to the substrate and a columnar structure were observed by the fractured cross-sectional view of the SDC films on NiO-YSZ anode substrate. Electrical conductivity of SDC film with 5 microm thickness was observed to be 2.31 x 10(-3) Sm(-1) at 800 degrees C.

Self-healing interconnects for flexible electronics applications

In this paper, we present the results of a study of self-healing flexible interconnect structures which utilize silver metallization on thin solid electrolyte films. Silver/electrolyte (Ag–Ge–Se) bilayers were fabricated on polyimide substrates and subsequently damaged by small radius bending. A small bias was used to stimulate Ag electrodeposition in the stress-induced cracks, thereby repairing the electrical discontinuity and returning the interconnect to a resistance close to its initial (unbroken) value. The healed structures were shown to be stable for small signal DC and AC conditions but were unable to withstand long periods of increased DC voltage stress due to interconnect erosion by ion migration.

Discharge characteristics of polymer blend (PVP/PVA) electrolyte films doped with potassium bromide

Solid polymer blend electrolyte films based on PVP/PVA complexed with KBr were prepared by the solution cast technique. Various experimental techniques such as electrical conductivity and transport number measurement were used to characterize the polymer electrolyte films. Electrochemical cells with the polymer electrolytes (PVP + PVA + KBr) were fabricated in the configuration K / (PVP + PVA + KBr) / (I2 + C + electrode). The discharge characteristics of the cells were studied under a constant load of 100 KΩ. The open-circuit voltage, short-circuit current, and discharge time for the plateau region are measured. Several other cell parameters were evaluated and are reported.

Characteristics of a new type of solid-state electrolyte with a LiPON interlayer for Li-ion thin film batteries

In this study, the feasibility of applying lithium phosphorous tungsten oxynitride (Li–P–W–O–N) thin films as solid-state electrolytes in solid-state ionic energy systems such as thin film batteries and super-capacitors was evaluated. The Li–P–W–O–N thin film electrolyte was prepared by radio frequency (RF) magnetron sputtering under various working pressures of nitrogen (N 2) reactive gas. We propose that the LiPON/Li–P–W–O–N/LiPON structure makes it possible to use a Li–P–W–O–N thin film as a thin film solid electrolyte because of the potential short circuiting of the Li–P–W–O–N thin film. To prepare the structure, a LiPON thin film was also deposited by RF magnetron sputtering onto Steel Us Stainless (SUS)/SiO 2/Si. When a LiPON thin film interlayer was deposited on the sandwich structure of the Li–P–W–O–N thin film electrolyte, the current was less than 1 μA. For the final cell structure of SUS/LiPON/Li–P–W–O–N/LiPON/SUS/SiO 2/Si, impedance measurements conducted at room temperature revealed ionic conductivities in the range of 1.5–1.2 × 10 − 7 Scm − 1 for the various deposition conditions of the Li–P–W–O–N thin films. This result suggests that the LiPON/Li–P–W–O–N/LiPON structured thin film electrolyte has potential as a solid oxide thin film electrolyte in solid-state ionic devices.